JPH05339020A - Manufacture of multilayer ceramic circuit board - Google Patents

Abstract

PURPOSE:To provide a manufacturing method of a multilayer ceramic circuit board which can form a thin insulating layer and can be made porous by introducing voids in the insulating layer, can have a low dielectric constant and can be produced at high speed and also which can form the insulating layer of a desired film thickness necessary for the circuit board when the insulating layer is formed by a sol-gel method, besides which can suppress rapid shrinkage of the film by accelerating a dehydrated condensation reaction when the insulating layer is formed by the sol-gel method, and which can suppress crack on the surface of the film and degradation of the strength. CONSTITUTION:This film porous ceramics are formed as the insulating layer on the base board by a thin film method and a thin film comprising a copper simple substance or essentially copper is formed as an electrically conductive body.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a multilayer ceramic circuit board, and more particularly, it can be applied to a mounting board for consumer electronic devices, a circuit board for computers, etc. The present invention relates to a method for manufacturing a multi-layer ceramic circuit board in which an insulating layer to be formed can be thinly formed and voids can be introduced into the insulating layer to make it porous.

In recent years, consumer electronic devices and computers have been required to have a circuit board capable of high-density mounting and high-speed transmission in response to the demand for higher speed and smaller size.

[0003]

2. Description of the Related Art In a conventional method for producing a multilayer ceramic circuit board, a ceramic powder, an organic binder and an organic solvent are mixed to prepare a slurry, which is spread on a carrier film and dried to obtain a green sheet. A sheet method or a thick film multi-layer method in which a paste-like material is screen-printed on a substrate to form a multi-layer structure is used.

[0004]

However, in the above-described conventional method for manufacturing a multilayer ceramic circuit board, the green sheet method and the thick film multilayer method are used, and the wiring density is limited. In the green sheet method, a soft sheet must be handled, and in the thick film multilayer method, screen printing is used, and both have a limited mechanical processing accuracy. For example, the wiring width is 70 μm or more, and the via diameter is 50.
It was possible to form only up to μm or more, and it was possible to form up to 100 μm or more in terms of insulating layer thickness.

Next, it is known that in order to reduce the dielectric constant of the ceramic material and increase the speed, it is possible to solve it by introducing voids into the insulating layer to make it porous. However, in order to use the material as a circuit board, it was necessary to form a thin insulating layer, but with the green sheet method or thick film multilayer method, as described above, it is possible to form only up to 100 μm or more. It was

By the way, with the recent demand for high-speed computer systems, a circuit board on which an LSI is mounted is also required to have a low dielectric constant and a high density.
In recent years, a multilayer ceramic circuit board has been developed and put into practical use in place of a resin board as a board that can be mounted at high density for a large computer. However, in conventional multi-layer ceramic circuit boards, alumina (dielectric constant
10), mullite (dielectric constant 7), and glass ceramics (dielectric constant 5 to 7) are used. These values have a higher dielectric constant than resins such as glass epoxy and polyimide (dielectric constant 3 to 4). For high speed signal transmission, lower dielectric constant materials have been desired. Therefore, a ceramic-resin thin film composite multilayer circuit board in which a polyimide resin thin film having a low dielectric constant is used as an interlayer insulating film on a ceramic substrate has been developed and used as a part of a circuit board for a large computer.

However, since the coefficient of thermal expansion of the conventional polyimide thin film multilayer circuit board is greatly different from that of ceramics, heat generated during computer operation causes stress on the interface between the ceramics and the polyimide on a large-sized board, resulting in reliability problems. There was a risk of problems. In addition, when the polyimide thin film is formed, the temperature should be 350 ℃ to 4 ℃ to cure the polyimide.
It was necessary to repeat the heat treatment process at 50 ° C. as many times as the number of layers of the interlayer insulating film. Therefore, in the case of a multilayer, repeated heat cycles may cause deterioration of the resin and short circuit of the wiring.

Further, in the conventional method for manufacturing a multilayer ceramic circuit board, a silicon alkoxide solution is dropped on the ceramic board, spin-coated, and dried in a thermostatic bath (after hydrolyzing reaction from sol to gel). If the sol-gel method of forming an insulating layer (vitrification) by heat-dehydration polycondensation reaction) and heat treatment is used, only a thin film of about 0.5 μm can be formed, and a desired film thickness required for a circuit board can be obtained. The insulating layer could not be formed. Then, if the number of coatings is increased to form a thick film, the film shrinks too much during the heat treatment, resulting in cracks or reduction in strength on the film surface.

Next, it is considered that the formation of the insulating layer by the sol-gel method causes cracks and a decrease in strength on the film surface for the following reason. The thin film by the sol-gel method is one in which a metal alkoxide and water are dissolved in alcohol, which is coated on a substrate and formed by a hydrolysis reaction. The hydrolysis reaction of this metal alkoxide and water is
Convert alkoxide to hydroxyl group. When these hydroxyl groups are present within a certain distance, a dehydration condensation reaction occurs and a film is formed.

However, the dehydration-condensation reaction is accompanied by a rapid shrinkage of the film, and unreacted hydroxyl groups that cannot be dehydrated-condensation reaction are localized in the film, so that cracks and reduction in strength occur on the surface of the film. It is estimated that Therefore, according to the first aspect of the present invention, the insulating layer can be formed thin (for example, with a film thickness of 10 μm or less) so that the conductor can be made into a fine wiring, and a void is introduced into the insulating layer to make it porous. In addition to achieving a low dielectric constant (dielectric constant of 3 or less) and accelerating the operation, the second aspect of the present invention, when forming the insulating layer by the sol-gel method, a desired film thickness (eg, An insulating layer having a thickness of 50 μm or less) can be formed, and further, in the third invention, when the insulating layer is formed by the sol-gel method, the dehydration condensation polymerization reaction is promoted to suppress the rapid shrinkage of the film. Therefore, it is an object of the present invention to provide a method for manufacturing a multilayer ceramic circuit board, which is capable of suppressing the surface cracking and strength reduction of the film.

[0011]

In order to achieve the above object, the method for manufacturing a multilayer ceramic circuit board according to the present invention is, in the first invention, formed by forming a thin film porous ceramics as an insulating layer on the board by a thin film method, and forming a copper simple substance. Alternatively, a composite thin film composed mainly of copper is formed as a conductor layer. In order to achieve the above object, the method for producing a multilayer ceramic circuit board according to the present invention is a second invention in which the board is prepared by a sol-gel method using a metal alkoxide solution forming a ceramic or glass to which spherical or acicular silica having a diameter of 10 μm or less is added. An insulating layer is formed on top, and a simple copper film or a composite thin film mainly composed of copper is formed as a conductor layer. The reason why the upper limit of the diameter of silica is set to 10 μm is that when the thickness is larger than 10 μm, the thickness of one insulating layer is about 50 μm, so that the structure is significantly different between the portion containing silica with a large silica diameter and the portion not containing silica. This is because the electrical characteristics change depending on the location, which is not preferable in practical use. The diameter of silica to be added is preferably 1 μm or less. In this case,
Ceramics with a homogeneous composition can be formed.

In order to achieve the above object, the method for manufacturing a multilayer ceramic circuit board according to the present invention has a diameter of 100Å in the third invention.
An insulating layer is formed on a substrate by a sol-gel method using a metal alkoxide solution that forms ceramics or glass to which ultrafine metal oxide particles are added, and a simple copper film or a copper-based composite thin film is formed as a conductor layer. It is a thing. Here, the upper limit of the diameter of the metal oxide ultrafine particles is set to 100.
The term Å means that if it exceeds 100Å, the dehydration condensation reaction is suppressed and a large amount of unreacted hydroxyl groups remain in the film, causing rapid shrinkage of the film and causing surface cracks and strength reduction of the film, which is not preferable for practical use. Because.

Examples of the substrate according to the present invention include a silicon wafer, an alumina substrate, glass, a ceramic composite and a multilayer ceramic substrate, and a substrate having a flat surface is preferable. Further, the thin film method includes CVD, sputtering, vapor deposition method, sol-gel method, alkoxide method, and the like, and as the inorganic substance which is the base material of the thin film porous ceramics, mullite, aluminum nitride, silica (including glass), Examples thereof include silica / ceramic composites and glass / ceramic composites.

In the copper-based composite thin film according to the present invention, Ti, Al, Cr, Ni, Ta and Au are formed above and below the copper film.
Such as a composite film formed by forming a metal film such as
It may be formed by sputtering, vapor deposition, plating or the like. In the present invention, the conductor via may be formed by a lift-off method, a laser cutting method, or the like.

In the first aspect of the present invention, as a method for making porous, a method of forming a mixture of an organic substance and ceramics, and then decomposing only the organic substance by heat treatment to make it porous, and ceramics There is a method in which only specific components therein are subjected to chemical etching later to make them porous. Alternatively, a method of depositing and forming a mixed layer of an organic substance and an inorganic substance such as ceramic or glass by a vapor phase method such as CVD, sputtering, or vapor deposition, and then decomposing only the organic substance by heat treatment to make it porous may be used. The inorganic substance and the inorganic substance may be simultaneously deposited on the substrate.

Further, a method for making the material porous will be specifically described. When the liquid phase method (sol-gel method, etc.) is used and the organic matter-containing method is used, first, a ceramic sol and an organic matter bead agitated product is formed into a film by spin coating and dipping, followed by gelation and heat treatment (heat treatment is 1000 ° C or less. , Nitrogen is performed) to scatter the organic beads in the film to form voids in the scattering traces to make the film porous. Further, in the case of using the liquid phase method (sol-gel method or the like) and the chemical etching method,
First, a sol having a glass composition that undergoes spinodal decomposition is formed into a film by spin coating and a dipping method, subjected to gelation and heat treatment (heat treatment is performed at 1000 ° C. or lower in nitrogen), and then acid treatment to make it porous. When using the vapor phase method and the organic matter-containing method, first, ceramics and organic matter are simultaneously sputtered to form a sputtered film, and heat treatment is performed at 1000 ° C or less in nitrogen to scatter the organic matter. It becomes porous by forming voids in it. Furthermore, when the vapor phase method and the chemical etching method are used, first, glass or ceramics having a composition that causes spinodal decomposition is sputtered to form a sputtered film, and then heat treatment is performed at 1000 ° C.
Then, the treatment is carried out in nitrogen, and the treatment is acidified to make it porous.

In the present invention, as a raw material of the sol-gel method for forming a ceramic or glass, ethyl silicate (Si (C ₂ H ₅ O) ₄ ) or aluminum alkoxide (Al (OC ₃ H ₇ ) is used as a metal alkoxide. ) ₃ ) Methoxy boron _{(B (OCH 3) 3)} , sodium alkoxide (NaOCH ₃₎ Etc. Further, an inorganic compound such as boric acid or sodium carbonate forming an aqueous solution for lowering the softening point of the glass can be used. Inorganic substances such as mullite and aluminum nitride may be dispersed and mixed in the metal alkoxide solution as the base material of the porous ceramics, or
A method of mixing a plurality of metal alkoxides may be used.

The present invention can be preferably applied to a multilayer ceramic circuit board in which at least two or more insulating layers and conductor layers are alternately stacked and wiring between upper and lower layers is formed by via holes (through holes). ..
In the second invention of the present invention, an insulating layer is formed on a substrate by a sol-gel method using a metal alkoxide solution for forming ceramics or glass to which spherical or acicular silica having a diameter of 10 μm or less, preferably 1 μm or less is added. However, it is also possible to form a simple thin film of copper or a composite thin film mainly composed of copper as a conductor layer, and further add a dispersant and a thickener to the alkoxide solution. In this case, the dispersant and the thickener are thickened. The viscosity can be further increased as compared with the case where no agent is added, and a thick insulating layer (15 μm or more) can be formed.

In the present invention, a foaming agent may be added to the alkoxide solution, or glass or ceramic hollow microspheres may be added to the alkoxide solution. In these cases, fine bubbles and air are introduced into the formed insulating layer to reduce the dielectric constant, which is preferable.

[0020]

In the first aspect of the present invention, as shown in FIGS. 1 and 2 of Example 1 described later, the thin film porous ceramic 5 serving as an insulating layer is formed by the thin film method by the sol-gel method. The insulating layer of the thin film porous ceramics 5 can be formed thinner than in the case of the conventional green sheet method and thick film multilayer method. Moreover, when it is fired to be ceramicized (including vitrification, glass-ceramic conversion, and ceramic conversion, hereinafter referred to as ceramic conversion), from a sol in which beads of thermally depolymerizable resin such as acrylic resin are dispersed. Since the acrylic resin beads dispersed in the film from the formed resin bead-containing body gel layer are scattered by thermal depolymerization to be made porous to form the thin film porous ceramics 5, the insulating layer of the thin film porous ceramics 5 is formed. It is possible to lower the dielectric constant and to increase the speed.

Next, in a second invention of the present invention, an insulating layer is formed by a sol-gel method using an alkoxide solution containing 0.1 μm silica spherical fine particles, as in Example 2 described later. Since the silica spherical fine particles that do not shrink even when heat-treated in the metal alkoxide solution are added, the viscosity of the solution itself can be increased more than when the silica spherical fine particles of the comparative example are not added, and the film shrinks even when heat-treated. The rate can be moderated. Therefore, the insulating layer having a desired film thickness necessary for the circuit board can be formed thicker. Moreover, since the inorganic insulating layer made of glass or glass ceramic is formed, it is possible to improve the moisture resistance and mechanical strength as compared with the case of the insulating layer made of resin.

Next, in the third invention of the present invention, since ultrafine silica particles having a diameter of 200 nm are added to a metal alkoxide solution forming a ceramic or glass as in Example 5 described later, dehydration condensation reaction is performed. It can be promoted to leave almost no unreacted hydroxyl groups in the film, rapid contraction of the film can be suppressed, and surface cracks and strength reduction of the film can be suppressed.

[0023]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings. (Embodiment 1) FIGS. 1 and 2 are views for explaining a method for manufacturing a multilayer ceramic circuit board according to Embodiment 1 of the present invention. 1 and 2, 1 is a substrate such as a silicon wafer (alumina, alumina / glass composite, low temperature fired multilayer ceramic circuit substrate may be used), 2 is a resist formed on the substrate 1, and then 3 Is a gel layer containing gelled acrylic resin beads (hereinafter referred to as ceramic film 3). Reference numeral 4 denotes an opening which is formed in the ceramic film 3 and serves as a via in which the wiring 4l on the substrate 1 is exposed. Reference numeral 5 denotes the acrylic resin beads in the ceramic film 3 being scattered and the ceramic film 3 being further made into a ceramic. It is a thin film porous ceramic which becomes an insulating layer formed by vitrification. Reference numeral 6 denotes a copper film formed over the thin film porous ceramics 5 from inside the opening 4 so as to come into contact with the wiring 1 of the substrate 1 inside the opening 4.

Next, a method of manufacturing the multilayer ceramic circuit board will be described. First, as shown in FIG. 1A, a negative resist is applied onto a substrate 1 such as a silicon wafer having a wiring pattern formed thereon, dried and pre-baked to form a resist layer 2. Then, as shown in FIG. As shown, photomask M
After masking and exposing, the non-exposed portion of the resist 2 is removed with a developing solution such as an alkaline solution, rinsed, washed, and post-baked to form a resist pattern, as shown in FIG. 1C.

Next, as shown in FIG. 1 (d), ethoxysilane, aluminum chloride, and a catalyst (hydrochloric acid, ammonia, etc.) are added.
5 vol% of acrylic resin beads having a diameter of about 5 μm which is thermally decomposed at about 600 ° C. is added, and this is spin-coated to form a film, which is then left at 45 ° C. for 20 hours to gel to form the ceramic film 3. The film thickness is 25 μm. Next, as shown in FIG. 2E, the resist 2 is removed by washing with a solvent to remove the substrate 1
An opening 4 is formed which becomes a via in which the upper wiring 4l is exposed.

Next, as shown in FIG. 2 (f), 600 ° C.,
The thin film porous ceramic 5 is formed by heat-treating at 900 ° C. for 2 hours in nitrogen for 1 hour to scatter the acrylic resin beads in the ceramic film 3, and at the same time vitrify or glass-ceramic the ceramic film 3. The film thickness is
It is 15 μm. Next, as shown in FIG. 2G, the copper film 6 is formed from the inside of the opening 4 into a thin film porous film by sputtering so as to come into contact with the wiring 1 of the substrate 1 in the opening 4, and then photoetching for patterning. Ceramics 5
Form over.

Then, in the same manner as above, the formation of the opening 4, the thin film porous ceramics 5 and the copper film 6 is carried out by the above process step (a).
By repeatedly forming as shown in (g) to (g) to form a multilayer, a multilayer ceramic circuit board as shown in FIG. 2 (h) can be obtained. As described above, in this embodiment, since the thin film porous ceramics 5 serving as an insulating layer is formed by using the thin film method by the sol-gel method, the thin film porous ceramics are more porous than those in the conventional green sheet method and thick film multilayer method. Ceramics 5
The insulating layer can be thinly formed. Moreover, since the acrylic resin beads dispersed in the film are scattered at the same time when the film is made into ceramics to make the ceramic film 3 porous to form the thin film porous ceramics 5, the dielectric layer of the insulating layer of the thin film porous ceramics 5 is formed. The rate can be lowered and the speed can be increased.

With respect to this speedup, the following results could be obtained. For example, a multilayer wiring pattern with a length of 20 cm (copper is formed and its transmission characteristics are
It was 8.0 ns / m for the circuit board (glass ceramics) formed by the conventional green sheet method, while it was 6.2 ns / m for the circuit board of the present invention. did it.

Next, the second embodiment of the present invention will be described with reference to Example 2 as described later, in comparison with a comparative example, which is a method of forming an insulating layer by a sol-gel method. First, a comparative example will be described. (Comparative Example 1) Ethyl silicate 37.6 g, ethanol 25
g, 45 g of water, and 0.3 g of hydrochloric acid are stirred to form a silicon alkoxide solution, and this silicon alkoxide solution is dropped onto a ceramic substrate and spin-coated, and then 200 in a constant temperature bath.
After drying at ℃ for 5 hours and dehydration polycondensation reaction from sol to gel, the temperature is raised to 800 ℃ in a nitrogen atmosphere for 24 hours and 800 ℃.
Heat for 2 hours to vitrify. In this way, a thin insulating layer of 0.5 μm was formed by coating once.
Then, a photoresist is applied to the insulating layer and reactive ion etching or hydrofluoric acid is used to form a through hole for establishing conduction with the lower layer.
A pattern is formed with a sputtered film of copper or the like. By repeating this, a multilayer ceramic circuit board was formed. In this comparative example, the insulating layer could be formed only with a thin film of about 0.5 μm, and the insulating layer with a desired film thickness necessary for the circuit board could not be formed. When the number of coatings is increased to form a thick film, the film shrinks too much during the heat treatment, causing cracks or the like in the film. (Example 2) The diameter of the alkoxide prepared in Comparative Example
20 g of 0.1 μm silica spherical fine particles are added and stirred, and the alkoxide solution to which the silica spherical fine particles are added is spin-coated on a ceramic substrate in the same manner as in the comparative example, and heat treatment is performed. That is, ethyl silicate 37.6g, diameter 0.1
20 g of spherical silica microparticles of 25 μm, ethanol 25 g, water 45
g, hydrochloric acid 0.3g is stirred to make a silicon alkoxide solution, and this silicon alkoxide solution is dropped onto a ceramic substrate and spin-coated, and dried at 200 ° C for 5 hours in a thermostatic layer to hydrolyze the sol into a gel. After that, the temperature is raised to 800 ° C. in a nitrogen atmosphere in 24 hours and heated at 800 ° C. for 2 hours to vitrify. Thus, a thin insulating layer having a thickness of 2 to 5 μm was formed by coating once. Then, this process was repeated four times to form an insulating film having a film thickness of 17 μm. Then, a multilayer ceramic circuit board was formed through the same steps as in the comparative example. That is, a photoresist is applied to the insulating layer, reactive ion etching or hydrofluoric acid is used to form a through hole for establishing conduction with the lower layer, and then a sputtering film of copper or the like is formed on the through hole. To form. By repeating this, a multilayer ceramic circuit board was formed.

As described above, in this example, the insulating layer is formed by the sol-gel method using the alkoxide solution to which the spherical silica fine particles of 0.1 μm are added. in this way,
Since silica spherical fine particles that do not shrink even when heat-treated in the alkoxide solution are added, the viscosity of the solution itself can be increased more than when the silica spherical fine particles of the comparative example are not added, and the amount of shrinkage of the film even when heat-treated. Can be relaxed. Therefore, the insulating layer having a desired film thickness can be formed on the circuit board. Moreover, since the insulating layer made of (ceramicized) glass is formed, the moisture resistance and the mechanical strength can be improved as compared with the insulating layer made of polyimide resin or the like. (Example 3) When an alkoxide solution containing spherical silica particles having the composition shown in Example 2 was prepared, 3 g of water was previously added.
Add a solution of boric acid (may be methoxyboron, etc.) and 0.4 g of sodium carbonate (may be sodium alkoxide, etc.). After that, coating was performed in the same manner as in Example 2, and then the coating was heated to 550 ° C. for 20 hours in a nitrogen atmosphere. In this way, an insulating film having a film thickness of 5 μm was formed by coating once. Then, a multilayer ceramic circuit board was formed through the same steps as in Example 2.

In this embodiment, the same effect as in Embodiment 2 can be obtained, and since boric acid and sodium carbonate are added, the heating temperature for vitrification is 800 in the case of Embodiment 2.
It can be performed at low temperatures, such as ℃ to 550 ℃. Example 4 After forming a film by adding a silane coupling agent (dispersing agent) and a thickener such as polyethylene glycol to the composition shown in Example 3 and spin coating or dipping in a solution. Then, this was similarly heat-treated to form an interlayer insulating film having a film thickness of 20 μm.
Then, a multilayer ceramic circuit board was formed through the same steps as in Example 3.

In this example, the same effects as in Example 3 can be obtained, and since a dispersant and a thickener were further added to the alkoxide solution, coating was performed once more than in Examples 2 and 3. Can further increase the thickness of the insulating layer. (Fifth Embodiment) The third invention of the present invention will be described with reference to the following embodiments. This example is particularly effective in forming a thin film without cracks.

4 mol of water was dissolved in ethanol with respect to 1 mol of tetraethoxysilicate which was a metal alkoxide. To this, silica fine particles (Comparative Example 2) manufactured by Nippon Steel Chemical Co., Ltd. having a diameter of 0.3 μm, and ultrafine silica particles having a diameter of about 200 nm synthesized by the sol-gel method were added and dispersed.
A film of about 0.1 μm was formed on a silicon wafer by a spin coater. In addition, Comparative Example 3 is one in which a film of about 0.1 μm was formed on a silicon wafer by a spin coater without adding silica fine particles. Then, the shapes of the films of the present invention and Comparative Examples 2 and 3 were analyzed by SEM, and the structures were analyzed by FT-IR. As shown in FIG. 3, in the FT-IR spectrum, an absorption band of a hydroxyl group was observed around 3360 cm ⁻¹ . As can be seen from FIG. 3, in the case where the silica fine particles of Comparative Example 3 were not dispersed,
An absorption band of unreacted hydroxyl groups was observed in the film, but when the ultrafine particles of the present invention were dispersed, the absorption band was almost disappeared. Further, in the case where the silica fine particles having a particle diameter of 0.3 μm in Comparative Example 2 were dispersed, this absorption band was rather increased as compared with the case where the silica fine particles in Comparative Example 3 were not added. This means that if the particles are larger than the film thickness of the insulating layer, the film formation is rather hindered. The results supporting the above can be obtained from the SEM photographs.
That is, in the case where the silica fine particles of Comparative Example 3 were not dispersed, the bondability with the silicon wafer was good, but many cracks due to the shrinkage of the film were observed, but when the silica ultrafine particles of the present invention were dispersed. , Good with silicon wafer,
It was confirmed that the film was uniform with almost no cracks. On the other hand, when the silica fine particles having a particle diameter of 0.3 μm in Comparative Example 2 were dispersed, it was confirmed that the bond with the silicon wafer was poor and many cracks were generated.

As described above, in this embodiment, since ultrafine silica particles having a diameter of 200 nm were added to the alkoxide solution, it is possible to accelerate the dehydration condensation reaction and to leave almost no unreacted hydroxyl groups in the film. It is possible to suppress the rapid shrinkage of the film, and to suppress the surface crack and the strength decrease of the film.

[0035]

According to the first aspect of the present invention, the insulating layer can be thinly formed, and voids can be introduced into the insulating layer to make it porous, thereby lowering the dielectric constant and increasing the speed. There is an effect that can be done. Further, according to the second aspect of the present invention, when the insulating layer is formed by the sol-gel method, there is an effect that the insulating layer having a desired film thickness necessary for the circuit board can be formed. Furthermore, according to the third aspect of the present invention, when the insulating layer is formed by the sol-gel method, it is possible to accelerate the dehydration condensation reaction and suppress abrupt shrinkage of the film, thereby preventing surface cracking and strength reduction of the film. There is an effect that it can be suppressed.

[Brief description of drawings]

FIG. 1 is a diagram illustrating a method for manufacturing a multilayer ceramic circuit board according to a first embodiment of the present invention.

FIG. 2 is a diagram illustrating a method for manufacturing a multilayer ceramic circuit board according to the first embodiment of the present invention.

FIG. 3 shows FT-I in the film of the present invention and Comparative Examples 2 and 3.
It is a figure which shows R spectrum.

[Explanation of symbols]

 1 Substrate 2 Resist 3 Ceramic Film 4 Opening 5 Thin Film Porous Ceramics 6 Copper Film

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Nobuo Kamehara 1015 Kamiodanaka, Nakahara-ku, Kawasaki-shi, Kanagawa Fujitsu Limited

Claims (6)

[Claims] 1. A method for producing a multilayer ceramic circuit board, comprising forming a thin film porous ceramics as an insulating layer on a substrate by a thin film method, and forming a simple copper film or a composite thin film mainly containing copper as a conductor layer. .. 2. An insulating layer is formed on a substrate by a sol-gel method using a metal alkoxide solution forming ceramics or glass to which spherical or acicular silica having a diameter of 10 μm or less is added, and copper alone or copper-based composite is formed. A method for manufacturing a multilayer ceramic circuit board, which comprises forming a thin film as a conductor layer. 3. The method for producing a multilayer ceramic circuit board according to claim 2, wherein a dispersant and a thickener are added to the alkoxide solution. 4. The method for manufacturing a multilayer ceramic circuit board according to claim 2, wherein a foaming agent is added to the alkoxide solution. 5. The method for manufacturing a multilayer ceramic circuit board according to claim 2, wherein glass or ceramic hollow microspheres are added to the alkoxide solution. 6. A copper-based or copper-based composite having an insulating layer formed on a substrate by a sol-gel method using a metal alkoxide solution forming ceramics or glass to which ultrafine metal oxide particles having a diameter of 100 Å or less are added. A method for manufacturing a multilayer ceramic circuit board, which comprises forming a thin film as a conductor layer.